Houston Methodist terminated me.

So I accept the job offer, give them my SSN, high school diploma, etc and do a medical screening consisting of blood draw, skin testing, urine sample, and I even had to take vaccines. On February 25th, I was supposed to get an email for orientation that will be on Monday March 1st. Mind you, I am working at the moment as well— I take care of 9 toddlers (all one year olds). I wait all day desperately for the email on Friday so I can take a day off from the children so I can make time for the orientation. No email. I wait all day Saturday, no email. I then wait Sunday, no email. It is Monday. They now remembered email me orientation info 5 mins before the meeting at 8am. I was supposed to get this email Friday so I can register for the orientation and see the timings. But no, I get it late and 5 mins before the meeting. Passing the deadline. If I knew orientation was going to be this time, I would’ve cleared my morning. Would’ve had somebody to take care of my 9 kids. The HR employee didn’t send the email on time. Who do I even talk to. What do I do?